David Drubin and other members of the Cell Polarity consortium have proposed constructing activation domain and binding domain fusions of about 100 proteins involved in bud development and cell division. All possible pairs will be tested systematically for two-hybrid interactions. Each member of the consortium has been assigned a number of baits to construct. While baits are being constructed, we will make the activation domain fusion constructs or pick them from the yeast activation domain array and verify them by analytical PCR and sequencing. The following genes have been proposedto be included in this experiment: Proteins involved in signalling: CDC42, CDC42-GTP, CDC42-GDP, CDC24, BOI1, BOI2, RHO1, RHO2, RHO3, RHO4, ROM1, MSB3, MSB4, BEM1, STE20, CLA4, SKM1, GIC1, GIC2, BEM2, BEM3, RGA1, MSB1, MSB2, BNI1, RSR1, BUD2, BUD5, ZDS1, ZDS2, FAR1. Actin and associated proteins: ABP1, CAP1, CAP2, SRV2, SLA2, SLA1, COF1, CRN1, MYO1, MYO2, MYO3, MYO4, MYO5, SAC6, ACT1, ARP2, ARP3, RVS167, AIP1, AIP2, AIP3/BUD6, PFY1, LAS17, IQG1. Proteins involved in secretion: SEC1, SEC2, SEC3, SEC4, SEC5, SEC6, SEC8, SEC9, SEC10, SEC15, SNC1, SNC2, SSO1, SSO2. Septins: CDC3, CDC10, CDC11, CDC12, SEP7, BUD3, BUD4 Proteins involved in bud site selection: BUD3, BUD4, BUD7, BUD8, BUD9, BUD10 We have so far received Gal4-DNA binding domain constructs of the following proteins from Clarence Chan: GIC1, GIC2, MSB2, BEM3, RGA1, and RSR1.